The Master Plan
by wolfgirlmusic
Summary: Sherlock/Doctor Who/Harry Potter crossover. The Master creates a device to send the Doctor to another universe, but it backfires and strands him and the Doctor in Sherlock's universe. He makes another attempt, but winds up in the Harry Potter world, taking characters from Sherlock along. Hilarity ensues!
1. Chapter 1

_Hey kids! Wolf Girl here, and I'm excited to bring you this crossover fan fiction. My three favorite fandoms are Doctor Who, Sherlock, and Harry Potter, and I finally found a way to intricately weave them together. I'd like you to keep in mind that this is being written for the fun of it, so it will be light-hearted and amusing for those who enjoy these characters (oh but don't worry, I may pull a Moffat or two ;) )_

 _Anyways, I'll write as often as possible, and any/all reviews are much appreciated._

 _Cheers!_

Cutlery clinked as Jim Moriarty savored his dinner. He cheerfully hummed _Staying Alive_ by the Bee Gee's as he lifted a water glass to his thin, dangerous lips. Footsteps could be heard approaching from behind; Moriarty's behavior did not deviate, but it was obvious that wheels were turning in his head. He returned the glass to the table, and said "Ooohh... I have no idea how you got in here..." He sprang out of his seat like a jack-in-the-box. He turned to face the intruder with a huge, maniacal grin. "But I love it! I absolutely love it! Can I offer you a splash of tea? A biscuit?"

The intruder was a man, standing statuesque in a doorway. He was well dressed in a tailored suit and his appearance was well groomed. Jim Moriarty practically danced over to him. "How did you do it? Why are you here? Who are you?"

The man smirked a little bit. "My, you are an excitable one, aren't you?" Moriarty pursed his lips and his eyes bulged with anticipation. The man sighed. "Some people know me as Harold Saxon, but I prefer to be called the Master."

"Mmm that's a bit grandiose..." mumbled Moriarty as he began methodically pacing around the Master. "And you are here why?"

"You have something of mine. I need it back."

Moriarty grimaced. "Oh, well, you know, finders keepers."

"Ugh, you humans..." The Master rolled his eyes. "You don't understand the severity of the situation." He cleared his throat and straightened himself out. "I am time lord from the planet Gallifrey. I went through great lengths to obtain a universe jumper. However, it backfired, and now I'm stuck here. I need it back so I can fix it and return to my universe."

Moriarty stopped pacing. His eyes bore into the Master's and he cocked his head like a puppy does when they are confused. "Say what now?"

"Listen to my chest, I have two hearts."

Moriarty gasped. "But sir, I hardly know you!"

The Master groaned and grabbed Moriarty's head, pulling his ear to his chest. Wide eyed, he listened to one side of his chest, slid over to the other side, and sure enough, there was a second heartbeat. Moriarty huffed as he pulled back. "Wow, and I thought _I_ was a freak..." He took a few steps back, crossed his arms, and became serious. "So now that I know what that thing is, what's to stop me from killing you right here and use it for my own person gain?"

The master scoffed and explained "Well you can't kill me, I'm a time lord. I'll just simply regenerate."

"Oh, fun! Let's test that theory, shall we?" In one fluid motion, Moriarty drew a pistol and fired it directly into the Master's chest.

A very disgruntled woman in a man's suit that sagged loosely over her body sat across from Jim Moriarty. Moriarty was leaning his face on his hands, gazing at her, completely enamored. "This... is... incredible!" laughed Moriarty, clapping his hands. "You can't die, you just burst into this fancy fairy light and form a new body?"

"Essentially..." she answered. She began loading her tea with a ridiculous amount of sugar.

"And you have this nemesis that has a vessel that can travel through space and time who keeps thwarting all of your evil plans?"

"Yes."

"So you made a device that disables his machine, catapults him into a parallel universe, and traps him there... but it backfired and you got dragged along."

"Yes, this is exactly what I just told you. I'm sorry if your tiny human brain has a hard time grasping this." She took a sip of her tea. "It didn't disable the TARDIS, so he's still flying around this universe. I want his TARDIS completely disabled, and I want to go back to my universe. So, I need my device back."

Moriarty smiled wide and leaned back in his chair. "Tell you what. I'll give you access to your little machine and I won't have a sniper blow your head off if you show me how it works. Let me watch you fix it."

She shrugged her shoulders. "Ok. It's not like you'll be able to understand it anyway."

"Also," he continued darkly, "I have a little nemesis of my own who could stand to be thrown into another universe."


	2. Chapter 2

"So you saw the police box materialize out of thin air, and then three people walked out of it."

"Aye, Mr. Holmes."

John exchanged glances with Sherlock. "And when did this happen?"

"Just this morning." The heavyset man squirmed in the chair. "In Hyde Park. I've got a photo." He withdrew his cell phone from his jacket pocket and started looking at his pictures. Sherlock focused on him with cold, calculating eyes.

"Here," said the man, handing his phone over. John huddled over to view the small screen with Sherlock. A cobalt blue, old fashioned police box was situated between two trees. Neither Sherlock nor John had noticed a police box in the park before.

"Hhhhmm…" Sherlock thought as he twiddled his fingers. He then stood up from his seat. "This is a four. I don't leave the flat for anything less than a seven. John, do you think you could go have a look around?"

John Watson was accustomed to it, so he didn't even bother fussing. Both he and the man stood up, and John motioned for the door, "After you."

They reached the park in fifteen minutes. The man was chattering on about an array of small things; Which internet browser he prefered, how his nephews were doing, the color of his cat's sick, etc. "It was just here…"

The man scratched his head as he came up to the trees. There was no blue police box to be found. However, John's eyes noticed someone on the ground. Instincts took over and he lept over to the person, rolling them over to see their face. They were definitely dead.

The Time Lady danced around the laboratory, snatching up various tools, and returning to the large piece of machinery in the center of the lab. Moriarty was watching her very closely.

"So tell me, Master, that device, once finished, will draw the TARDIS from anywhere?"

"Please," she insisted, "Call me Missy."

"All right… Missy…" he corrected himself. He observed her pouring liquid in a tube. "So we'll plant a body everywhere that thing lands, leaving little clues for Sherlock to find how they are connected. Once he figures out the pattern, he'll know when and where the next victim will be killed, and he will be waiting."

"And we'll call the TARDIS, he'll go barricading in like a vigilante, and then POOF… send it off to another dimension," completed Missy, pulling a lever and looking into Moriarty's eyes.

"I love it… this is brilliant!" smiled Moriarty.

"Yes yes, it's quite devious. I can't wait to get them out of here and go back to where I came from," said Missy as she picked up a wrench.

Moriarty waited for her to turn around before he wiped his grin away and went back to analyzing what she was doing.


	3. Chapter 3

"Slow down!" called John Watson, sprinting after Sherlock.

"No time, John!" exclaimed Sherlock in between pants. "That police box is going to be at our flat any second and I need to catch it!" The two of them had been chasing after this 'police box of doom' for the last few days. Everywhere it was spotted, a death would occur shortly after. Sherlock was confident he had worked out the algorithm of where it would happen next, and that just so happened to be 221B Baker street.

A strange, mechanical 'whooshing' noise could be heard as they rounded the corner. Sherlock barricaded through the front door of the building. He stopped dead in his tracks as his eyes feasted upon the cobalt blue police box.

"Sherlock!" wheezed John, holding himself up by the doorframe. He reached out to his friend in vain; Sherlock was bewitched. Slowly, boldly, Sherlock stepped towards the box. He drew in a deep breath.

He wasn't expecting to see much when he pushed the door in. His eyes narrowed as he was greeted by a huge, strangely constructed room. He couldn't help but to take another step inside. "Oh, hello! Wasn't expecting visitors…" called a man from the other side of the room. Sherlock could barely comprehend what was going on. Last time he checked, there wasn't an enormous, whirring, steaming, beeping room in his flat. Where did this come from?

John Watson apprehensively peered into the police box. His jaw hit the floor. He blinked a few times, just to make sure his eyes were working. "Oh, there's two of you then," said the strange man. John looked up to see three people on the other side of the room. The man that spoke up had on a tweed jacket, suspenders, and a bow tie. There was a strikingly beautiful woman with long red hair clutching onto a tall, lanky man with light brown hair. The man with the bow tie skipped down a small flight of stairs towards them. He stopped a few feet in front of the men and announced "Hello, I'm the Doctor, and welcome to the TARDIS! Now if you could just turn around and go back to where you came from, that would be lovely."

He started to usher them out, but the attempt was thwarted when the TARDIS door violently slammed shut. The entire place began to rumble and alarms started going off. "Doctor, I think it's happening again!" called out the red head. John pushed against the door, but it wouldn't budge. Sparks were flying everywhere and steam hissed out from the floor. "HOLD ON!" cried the Doctor.

"What's goin on?!" yelled Missy, shaking the device in her hands. "This should be just disabling it, why is it preparing to take off?!" Missy and Moriarty were perched atop the stairs in the flat. Missy was panicking, trying to figure out why her machine wasn't working. "Oh, yes, I suppose I should tell you…" said Moriarty, grimacing. "I may have sort have fiddled with your machine a bit."

Her posture tensed as she became filled with rage. "WHAT DID YOU DO?!"

An electric purple and blue energy began to glow around the TARDIS. A beam of the energy lashed out and ensnared Missy and Moriarty. "They're being sent to another universe, and I'm going with!" shouted Moriarty. "It's just so boring here!"

"YOU NINCOMPOOP!" screamed Missy as the TARDIS was hurled through space and time, dragging Moriarty and Missy behind.

Inside the TARDIS, everyone was holding on for dear life. Sherlock cried out to John "If this is how we die, in some bloody police box that's not really a police box, I just want you to know that I am grateful for everything you have done!"

"We're not going to die, Sherlock! Don't say that!"

"We very well possibly could though," called the Doctor, stumbling over some panels. "The defence shield is failing and we're having a massive surge through the power system…"

"Thanks…" murmured John under his breath.

There was one final, powerful jolt. Everyone's bodies were tossed around like rag dolls. It became pitch black inside the TARDIS; the only light was coming in through a crack in the door. The Doctor scrambled towards it, eager to poke his head out. They had landed in an enormous, stone dining hall. tables and seats were smashed where the TARDIS had skidded before finally crashing into a podium. The Doctor winced at the mess. He looked up and noticed lit candlesticks hovering innocuously in the air.

"Alright alright, everyone out," called the Doctor, "It's safe out here, not safe in there. Come along Ponds and… not Ponds."

The occupants of the TARDIS managed to make it out, bodies aching and sore. "Where are we?" questioned the man that was with the woman. "Are we in some kind of castle or something?"

"You're in Hogwarts, school of witchcraft and wizardry!" called a voice from the entrance. Everyone snapped their heads to see an elderly man with an impressive beard, garbed in a colorful, velvety robe. "Now, could you kindly tell me how you managed to get in here?"


End file.
